[Prediction of syncope with nonlinear dynamic analysis during head-up tilt in vasovagal syncope patients]

OBJECTIVE

To quantify the relationship between cerebral blood flow velocity and peripheral blood pressure during hypotension period, aiming to predict the brain hypotension before symptomatic occurrence.

METHODS

Twenty vasovagal syncope (VVS) patients who had a previous clinical history were selected in groups and 20 pair-matched control subjects underwent 70° tilt-up test. The subjects remained supine for 30 minutes before recordings when Doppler probes, electrodes and Finapres device were prepared. After continuous baseline recordings for 10 min, the subjects underwent head up tilt (HUT) test (70°), and were standing upright for 30 minutes or until syncope was imminent. For ethical reasons, the subjects were turned back to supine position immediately after SBP dropped to ≥20 mmHg, when their consciousness persisted. The point of syncope was synchronized for all the subjects by the point SBP reached the minima. Their beat-to-beat blood pressures (BP) were recorded continuously and bilateral middle cerebral artery (MCA) flow velocities were obtained with two 2 MHz Doppler probes from a transcranial Doppler ultrasonography (TCD) system. A nonlinear dynamic method--multimodal pressure flow (MMPF) analysis was introduced to access cerebral autoregulation during different time intervals. We introduced a new indicator--syncope index (SI), which was extracted from blood flow velocity (BFV) signal to evaluate the variation of cerebral vascular tension, and could reflect the deepness of dicrotic notch in BFV signal.

RESULTS

Compared with the syncope index of the baseline value at the beginning of the tilt test, SI in VVS group showed significantly lower when the VVS occurred (0.16±0.10 vs.0.27±0.10,P<0.01),while there was no significant difference in syncope index between the control group at the end of the tilt test and the baseline value at the beginning of the tilt test. For those VVS patients, pulse index and resistance index had no significant change. Syncope index decreased significantly 3 minutes before the point of syncope (0.23±0.07 vs.0.29±0.07,P<0.01).

CONCLUSION

Dynamic regulation is exhausted when vasovagal syncope occurred. Tension decrease of small vessels could have some relationship with loss of the cerebral autoregulation capability. The proposed syncope index could be a useful parameter in predicting syncope of VVS patients since it decreased significantly up to 3 minutes earlier from the point of syncope.

[Prevalence and attribution of high-risk HPV in different histological types of cervical cancer]

Objective: To investigate the prevalence of high-risk HPV subtypes in different pathological types of cervical cancer, and analyze the attribution of carcinogenic HPV subtypes in different pathological types. Methods: A total of 1 541 patients with cervical cancer were treated between February 2009 and October 2016 in Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. The median age at diagnosis was 49 years (ranged 20-82 years old). The numbers of patients with cervical cancer from North China, Northeast China, East China, Central China and other regions (including Northwest, Southwest and South China) were 961, 244, 175, 87 and 74 cases, respectively. Pathological types: 1 337 cases of squamous cell carcinoma (SCC), 87 usual adenocarcinoma (ADC), 23 adenosquamous carcinoma (ASC), 20 mucinous carcinoma (MC), 19 clear cell carcinoma (CCC), 12 endometrioid carcinoma (EC), 25 neuroendocrine carcinoma (NEC), 9 serous carcinoma (SC), 5 villous adenocarcinoma (VADC) and 4 minimal deviation adenocarcinoma (MDAC). The prevalence of high-risk HPV in different regions, age groups at diagnosis and pathological types in cervical cancer were analyzed. The attribution of 13 high-risk HPV subtypes in different pathological types of cervical cancer based on proportional attribution method, and the attribution of high-risk HPV subtypes prevented by 9-valent HPV vaccine in SCC and ADC were calculated. Results: (1) The prevalence of high-risk HPV in 1 541 patients with cervical cancer was 86.6% (1 335/1 541). The multiple high-risk HPV infection rate in patients with SCC ≥60 years old (23.0%, 37/161) was significantly higher than those in patients aged 45-59 years old and ≤44 years old [11.4% (85/747) vs 11.7% (50/429), P<0.01], and the high-risk HPV infection rates of patients with cervical cancer in North China, Northeast China, East China, Central China and other regions were respectively 86.8% (834/961), 87.7% (214/244), 83.4% (146/175), 83.9% (73/87) and 91.9% (68/74). SCC (86.8%, 1 337/1 541) and ADC (5.6%, 87/1 541) were the most common pathological types in cervical cancer. The high-risk HPV prevalence of SCC, ADC, ASC, MC, NEC and VADC were 90.1% (1 205/1 337), 74.7% (65/87), 87.0% (20/23), 65.0% (13/20), 72.0% (18/25) and 5/5 respectively. The high-risk HPV infection rates of SC, EC, CCC and MDAC were 4/9, 3/12, 2/19 and 0/4 respectively. (2) According to proportional attribution, HPV 16 (69.5%), HPV 18 (5.6%), HPV 58 (2.2%), HPV 31 (1.9%), HPV 52 (1.4%) and HPV 33 (1.3%) were the six common high-risk HPV subtypes in SCC. While, HPV 18 (44.1%), HPV 16 (20.5%), HPV 52 (2.3%), HPV 58 (1.2%) and HPV 51 (1.2%) were the main carcinogenic subtypes in ADC. The main carcinogenic high-risk HPV subtypes of ASC, NEC and MC were HPV 18 and HPV 16. The total attribution of HPV 16, 18, 31, 33, 45, 52 and 58 prevented by 9-valent HPV vaccine in SCC and ADC were 82.6% and 68.1% respectively; the attribution of HPV 45 in SCC and ADC were only 0.8% and 0. Conclusions: SCC and ADC are the main pathological types in cervical cancer. SCC, ADC, ASC, MC, NEC and VADC are closely related to high-risk HPV infection. HPV 16 is the main carcinogenic genotypes of SCC. HPV 18 maybe play an important role in the pathogenesis of ADC.

[Etiology and clinical technology of the food impaction with tight proximal contacts]

Food impaction with tight proximal contacts, also known as kinetic food impaction and food impaction without anatomical structure destruction, is mainly caused by a transient separation in contacts area during mastication. It's an intractable food impaction with high morbidity and low cure rate. There are two kinds of pathogenesis accepted: the shifting of anterior teeth incongruous with adjacent teeth or lack of anterior shifting; lack of food escape grooves. The preferred treatment is occlusal adjustment, but it's difficult to determine the area and extent of selective grinding, to quantify the occlusal adjustment, or to predict the prognosis. This review summarized the pathogenesis and treatment modality for kinetic food impaction in order to provide evidence for future researches and clinical application.

[Establishment of a 3D printing system for bone tissue engineering scaffold fabrication and the evaluation of its controllability over macro and micro structure precision]

OBJECTIVE

To establish a 3D printing system for bone tissue engineering scaffold fabrication based on the principle of fused deposition modeling, and to evaluate the controllability over macro and micro structure precision of polylactide (PLA) and polycaprolactone (PCL) scaffolds.

METHODS

The system was composed of the elements mixture-I bioprinter and its supporting slicing software which generated printing control code in the G code file format. With a diameter of 0.3 mm, the nozzle of the bioprinter was controlled by a triaxial stepper motor and extruded melting material. In this study, a 10 mm×10 mm×2 mm cuboid CAD model was designed in the image ware software and saved as STL file. The file was imported into the slicing software and the internal structure was designed in a pattern of cuboid pore uniform distribution, with a layer thickness of 0.2 mm. Then the data were exported as Gcode file and ready for printing. Both polylactic acid (PLA) and polycaprolactone (PCL) filaments were used to print the cuboid parts and each material was printed 10 times repeatedly. After natural cooling, the PLA and PCL scaffolds were removed from the platform and the macro dimensions of each one were measured using a vernier caliper. Three scaffolds of each material were randomly selected and scanned by a 3D measurement laser microscope. Measurements of thediameter of struts and the size of pores both in the interlayer overlapping area and non-interlayer overlapping area were taken.

RESULTS

The pores in the printed PLA and PCL scaffolds were regular and interconnected. The printed PLA scaffolds were 9.950 (0.020) mm long, 9.950 (0.003) mm wide and 1.970 (0.023) mm high, while the PCL scaffolds were 9.845 (0.025) mm long, 9.845 (0.045) mm wide and 1.950 (0.043) mm high. The struts of both the PLA and PCL parts became wider inthe interlayer overlapping area, and the former was more obvious. The difference between the designed size and the printed size was greatest in the pore size of the PLA scaffolds in interlayer overlapping area [(274.09 ± 8.35) μm)], which was 26.91 μm. However, it satisfied the requirements for research application.

CONCLUSION

The self-established 3D printing system for bone tissue engineering scaffold can be used to print PLA and PCL porous scaffolds. The controllability of this system over macro and micro structure can meet the precision requirements for research application.

[Computer aided design and three-dimensional printing for apicoectomy guide template]

OBJECTIVE

To establish an apicoectomy guide template design and manufacturing method, based on multi-source data fusion, computer aided design (CAD) and fused deposition modeling (FDM). The feasibility of the guide template was preliminary evaluated by the in vitro model experiment.

METHODS

An extracted upper anterior tooth, after root canal treatment, was optical scanned, after which the extracted upper anterior tooth was poured in an apicoectomy plaster model. Cone-beam computed tomography (CBCT) scanning of the apicoectomy plaster model was performed, after which optical scanning of the plaster model for apical resection surgery was carried out. All of the relevant CBCT and optical scanning data of the extracted upper anterior tooth and the apicoectomy plaster model were introduced into the Geomagic Studio 2012 software. The multi-source data fusion technology was used to virtually simulate the three-dimensional positional relationship of the extracted tooth, the dentition, the alveolar bone and the gingival, based on which, the three-dimensional design of the apicoectomy guide template was completed in the Geomagic Studio 2012 software. With the technology of fused deposition modeling, the apical resection surgical guide template was three-dimensionally printed with the material of polylactic acid (PLA). Under the guidance of the surgical guide template, the root apical resection was performed on the plaster model. After the apicoectomy, the extracted upper anterior tooth was taken off from the apicoectomy plaster model and then was given the optical scanning. The apical resection length and angle were calculated by the function of distance measurement and angle measurement, and the results were compared with the preset values.

RESULTS

The length of the apical resection was 2.88 mm along the direction of the long axis of the tooth, which was 0.12 mm lower than the preset 3 mm. The included angle between the apical resection plane and the long axis of the tooth was 77.9°, 12.1° lower than the preset 90°.

CONCLUSION

This study successfully established a digital design and production method of apicoectomy guide template by combing the multi-source data fusion, CAD and FDM technology. The design route and the production method are feasible. The study will provide a technology and methodology reference for the development of domestic special software for the digital design of apicoectomy guide template.

[A preliminary study on the three-dimensional trajectory of condyle]

Objective: To calculate the three-dimensional trajectory and motion morphology of condyle by combining the trajectory of the mandible movement and the three-dimensional model of the mandible. Methods: Cone beam CT (CBCT) scanning was performed on the volunteer. The mandible three-dimensional model was built with image data transferred to the graphical user interface of the computer workstation. The novel virtual articulator PN300 recorded the three-dimensional trajectory of mandible. All these data were transferred to software system of computer workstation calculating the three-dimensional trajectory of condyle. The motion morphology of condyle was simulated by merging function surface at each point. Results: When the mandible moved in an opening process, the recorded data was calculated and it was shown that: the condylar functional surface moved moved forward and downward inward in advance, and in the process of continuously increasing the opening degree, the function faced the front upper inner side. The straight-line distance between the position and the final position was 8.34 mm. During the forward movement of the mandible, the coracoid process slided forward downward and inward with a sliding distance of 8.64 mm. During lateral movement, the range of the working side condyle function surface motion was small, only slight rotation, the maximum range of motion was 1.97 mm; in the process of row side movement, the non-working condyle function surface had a larger movement range than the working side, the movement direction was the front lower inner side, and the movement distance was 7.65 mm. Conclusions: The novel virtual articulator PN300 and digital technology can achieve the accurate measurement of three-dimensional trajectory of the condyle, and furthermore simulate the motion morphology of the condyle.

Xuebijing enhances neuroprotective effects of ulinastatin on transient cerebral ischemia via Nrf2-are signal pathways in the hippocampus

Prior studies have demonstrated that ulinastatin (UTI) plays a beneficial role in regulating cerebral ischemic injury evoked by cardiac arrest (CA). It is noteworthy to find interventions that can enhance effects of this drug and thereby increase its clinical application. Xuebijing (XBJ) is comprised of extracts from Chinese herbs and has been widely used in China as an anti-endotoxicity drug for the treatment of sepsis and ischemic disorders associated with multiple organ dysfunction syndrome. Thus, in this study we examined the effects of a combination of UTI and XBJ to improve neural injury in the process of neurological functions after transient cerebral ischemia. Our results show that CA impaired Nrf2- antioxidant response element (Nrf2-ARE) and superoxide dismutase (SOD) in the hippocampus CA1 region. This process further amplified products of oxidative stress, namely 8-isoprostaglandin F2α (8-iso PGF2α) and 8-hydroxy-2'-deoxyguanosine (8-OHdG). A lower dose of UTI failed to restore Nrf2-ARE and attenuate 8-iso PGF2α and 8-OHdG SOD following CA; however, systemic administration of XBJ amplified the effects of this dose of UTI on antioxidative signal pathway of the hippocampus. Overall, the results of this study have implications for the enhanced neuroprotective role played by a combination of XBJ and UTI in improving neural injury observed in transient cerebral ischemia; and Nrf2-ARE signal is a part of key mechanisms that are involved in neuroprotective effects of XBJ and UTI.

[Airway inflammation and small airway wall remodeling in neutrophilic asthma]

OBJECTIVE

To investigate the distribution of airway inflammation phenotype in patients with bronchial asthma (asthma), and to analyze clinical characteristics, inflammatory cytokines, pulmonary small vessels remodeling and small airway wall remodeling in patients with neutrophilic asthma.

METHODS

Sixty-three patients with asthma were enrolled from January 2015 to December 2015 in Peking University Third Hospital. Clinical data including gender, age, body mass index (BMI), pulmonary function tests (PFTs), asthma control test (ACT) were recorded. All the patients underwent sputum induction. The cellular composition of the sputum was evaluatedand the concentration of active MMP-9 in the sputum tested. Blood routine tests were done and the concentration of IgE, periostin, and TGF-beta1 levels were measured in serum by enzyme-linked immunosorbent assay (ELISA). Small airway wall remodeling was measured in computed tomography (CT) scans, as the luminal diameter, luminal area, wall thickness and wall area % adjusted by body surface area (BSA) at the end of the 6th generation airway, in which the inner diameter was less than 2 mm. Small vascular alterations were measured by cross-sectional area (CSA), and the total vessel CSA < 5 mm² was calculated using imaging software.

RESULTS

The distributions of airway inflammatory phenotypes of the asthmatic patients were as follows: neutrophilic asthma (34.9%, 22/63), eosinophilic asthma (34.9%, 22/63), mixed granulocytic asthma (23.8%, 15/63), and paucigranulocytic asthma (6.3%, 4/63). The neutrophilic subtype patients had a significantly higher active MMP-9 level in sputum compared with the eosinophilic phenotypepatuents, as 179.1 (74.3, 395.5) vs. 50.5 (9.7, 225.8), P<0.05. Sputum neutrophil count was negatively correlated with FEV1%pred (r=-0.304,P<0.05), and positively correlated with active MMP-9 level in sputum (r=-0.304, P<0.05), and positive correlation trend with airway wall thickness (r=0.533, P=0.06). There was a significantly negative correlation of active MMP-9 level in sputum with FEV1%pred (r=-0.281, P<0.05), in positive correlation with small airway wall area (%)(r=0.612, P<0.05), and inpositive correlation trend with airway wall thickness (r=0.612, P=0.06). Neutrophils count in peripheral blood was positively correlated with neutrophil counts in sputum.

CONCLUSION

Neutrophil count in airway is related to lung function in asthmatic patients. Neutrophils may accelerate small airway wall remodeling through the release of active MMP-9. Neutrophil count in peripheral blood is related to neutrophils count in sputum, which may be used as a substitute for evaluating inflammatory phenotype.

[Preliminary study on the automatic preparation of dental implant socket controlled by micro-robot]

Objective: To analyze the quantitative relationship between the number of layers of laser pulses and the amount of step in ultra-short pulse laser cutting of cortical bone, optimize the robot's vertical single stepping parameters, and to explore the feasibility of automatic preparation of dental implant cavity using robot controlling ultra-short pulse laser, in order to lay the foundation for automated dental implant surgery. Methods: Eight pig ribs were segmented into to make 16 specimens. Using the robotic surgical system and path planning software independently developed by our group, circular holes with a diameter of 4 mm were cut two-dimensionally in the rib segments to obtain the quantification relationship of the number of laser pulse layers (n) and the depth of two-dimensional (2D) cutting (d). When conducting the three-dimensional (3D) cutting procedure, the number of pulse layers were set to 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 layers, the vertical single step amount was an integer value corresponding to the results of 2D cutting depth, and the number of pulses (n') corresponding to the minimum difference between the theoretical depth of cut and the actual depth of cut was obtained. The n' was taken as the most suitable single step pulse layer, the rib segment was cut, and the depth of single cut was measured while the integer value was taken as the most appropriate vertical single step amount (d'). The vertical parameters of laser single stepping were set as n' layer pulse and d' μm step size. The 3D cutting produces a cylindrical cavity with a diameter of 4 mm and a height of 2 mm to evaluate the 3D cutting accuracy (the difference between the measured value and the theoretical value of cutting diameter or depth). Ten 4 mm×3 mm implant holes were automatically prepared on the bilateral femurs of 5 Japanese big white rabbits, and ten 4 mm×3 mm implants made by 3D printer were artificially implanted, and the preparation effect of the implant cavities was evaluated. Results: The quantitative relationship curve between the number of laser pulses (n) and 2D depth of cut (d) showed a linear upward trend. The linear fitting obtained the quantitative relation function formula d=9.278 4 n±26.763 0, R(2)=0.988 9. The optimum number of single step pulse layers was 5 layers, and the vertical single step amount was 50 μm, so as to set the vertical parameters of a single step of a 3D cutting, and the 3D cutting diameter accuracy was (3.98±2.87) μm, with a depth accuracy of (15.42±5.44) μm. Automated preparation of 10 implant cavities on the femur of the rabbit were completed. When the implants were placed into the implant cavities, there was resistance, but they were fully seated and primary stability has been achieved after seating implant placement. Conclusions: The method of non-contact automatic preparation of dental implant cavities using robot controlling ultra-short pulse laser is feasible. By optimizing the single cutting process parameters, precise control of laser cutting cortical bone can be realized.

[Analysis of correlative factors of serum leptin levels in asthmatic patients]

Objective: To analysis the correlative factors that probably affect serum leptin levels in asthmatic patients. Methods: Seventy-eight patients with asthma and 29 health controls who were admitted into outpatient clinic of Peking University Third Hospital from April 2014 to December 2015 were consecutively enrolled in our study prospectively. Serum leptin level was measured by enzyme-linked immunosorbent assay (ELISA). The sex, body mass index (BMI), onset age of asthma, allergen detection test, induced sputum cell count and classification, lung function test and asthma control level were recorded. Asthmatic patients were further divided into groups according to these factors and serum leptin levels were compared among groups. Results: Serum leptin levels were not different between asthmatic patients and health controls [(15.0±10.4) vs (15.2±11.7) μg/L, P=0.939]. Female asthmatic patients had significantly higher serum leptin levels than male [(18.2±10.7) vs (7.9±4.8) μg/L, P<0.001]. Asthmatic patients with obesity had significantly higher serum leptin levels than asthmatic patients with overweight, with normal BMI, with underweight and health controls [(29.7±10.8) vs (17.1±11.1), (11.8±7.7), (9.1±0.96), (15.2±11.7) μg/L, all P<0.01]. Serum leptin level was positively related to percentage of induced sputum eosinophil in female asthmatic patients (r=0.331, P=0.032). Onset age of asthma, positive allergen detection, airflow limitation or asthma control level did not affect serum leptin level. Conclusion: Sex and BMI are important factors affecting serum leptin levels in patients with asthma.

[Influence of intraoral scan and dental cast scan on occlusal quantitative analysis of virtual dental model]

OBJECTIVE

To make more accurate occlusal quantitative analysis of three-dimensional (3D) virtual dental models and to compare the occlusal contact obtained by intraoral and dental cast scan.

METHODS

In this study, 5 subjects were intraoral scanned using laser scanner (3 shapes, Germany) to obtain the 3D virtual models of one tooth (the first molar), two teeth (the second premolar and the first molar), three teeth (the premolars and the first molar) and their opposite teeth, respectively. The silicone impressions were made and dental stone models were poured for each of them. The dental casts were scanned and then they were fixed to the maximum intercuspal position with a special locating jig for a rescanning of occlusal position. The virtual models taken intraorally and obtained with dental cast scan were introduced to a 3D quantitative analysis system, and some criteria regarding to occlusal contact were calculated and analyzed. The occlusal criteria were mean values of occlusal clearance space between the upper and lower occlusal surface (clearance), occlusal contact area (area), and cusp inclination (angle) of the mandibular first molar. Paired t tests were used to evaluate differences of occlusal criteria between the virtual models obtained with the intraoral scan and dental cast scan (α=0.05).

RESULTS

The mean values of occlusal clearance of one to three teeth obtained by way of intraoral scan were smaller than those obtained by way of cast scan by 0.134 mm, 0.177 mm, and 0.207 mm, respectively. While the occlusal contact areas were greater than the cast scan by 8.65 mm², 10.28 mm², and 11.46 mm². No statistically significant differences were found between the cusps inclinations obtained with the two scanning methods, and the interclass correlations were high.

CONCLUSION

Occlusal clearance obtained by intraoral scan was less than that by cast scan while the occlusal contact area was greater than the latter, indicating that intraoral occlusal contact was closer. The difference of the standard deviations of occlusal clearance measured by the two methods were small and that of occlusal contact area was influenced by the number of teeth scanned intraorally. There was no statistical difference in cusp inclination between the two methods.

[Research status of tooth preparation quantitative guide technique]

Tooth preparation is a basic operation in prosthodontics treatment and the quality of preparation influences the effect of treatment directly. How to achieve a precise and quantitative tooth preparation is always one of the main aims of dental prosthodontics. The known types of tooth preparation guide technique can be divided into visual guidance, passive constraint guidance and active constraint guidance (automated tooth preparation), respectively represented by silicon rubber index, tooth preparation guide plate and computerized numerical control cutting system (CNC cutting system). Studies in advanced manufacturing technologies such as robot systems and numerical control ultra-short pulse laser (USPL) have also been reported recently. This review comprehensively introduced tooth preparation quantitative guide techniques and partially summarized the application effects and limitations to provide reference for relative researches and clinical application.

[Research and development of digital design and fabrication of complete denture]

Removable complete denture are still the primary prosthetic solution for edentulous patients. Functional pressure impression obtaining, jaw relation recording, personalized balance occlusion and highly precise fabrication of denture are difficult. The digital restoration technique represented by intraoral three-dimensional scanning and three-dimensional (3D) printing compensates for the shortages of the manual techniques, but there are still many limitations in the application of complete dentures. At present, a few computer aided design and computer aided manufacture (CAD/CAM) complete denture systems have been developed both domestically and abroad, and these system are mainly focused on the digital design and manufacture of denture, and are seldom used for the recording of impression and jaw relation. This review is based on the main clinical procedures of the traditional complete denture restoration, elaborating the research and application status of digital technique in each steps, in order to provide reference for clinical application.

[Quantitative evaluation of printing accuracy and tissue surface adaptation of mandibular complete denture polylactic acid pattern fabricated by fused deposition modeling technology]

Objective: To quantitatively evaluate the adaptation of polylactic acid (PLA) pattern of mandibular complete denture fabricated by fused deposition modeling (FDM) technology. Methods: A mandibular complete denture digital model was designed through a complete denture design software based on a pair of standard maxillomandibular edentulous plaster model and their occlusion bases. Ten PLA mandibular complete dentures were printed with a FDM machine. The dentures were scanned with and without the plaster model using a three-dimensional (3D) scanner. In Geomagic software, the scanning data of printed dentures were registered to its computer aided design (CAD) data, and the printing error was analyzed using the multipoint registration command. For quantitatively evaluating the adaptation of the denture, the data of plaster model and PLA denture were registered to the whole data of denture located in the plaster model using the best-fit alignment command, the 3D deviation of the plaster model and tissue surface of the denture represent the space between them. The overall area was separated into three parts: primary stress-bearing area, secondary stress-bearing area and border seal area, and the average deviations of these three parts were measured. The values were analyzed using analysis of variance. Results: Compared with the CAD data, the printing error was (0.013±0.004) mm. The overall 3D deviation between PLA denture and plaster model was (0.164±0.033) mm, in which the primary stress-bearing area was (0.165± 0.045) mm, the secondary stress-bearing area was (0.153 ± 0.027) mm, the border seal area was (0.186 ± 0.043) mm. These showed a good fit in the majority parts of the FDM denture to the plaster model. No statistically significant difference was observed between the three areas (F=1.857, P=0.175>0.05). Conclusions: Combined with the 3D scanning, CAD and FDM technology, a FDM 3D printing process of complete denture for injection moulding can be established. As a result, high efficiency and low cost can be used to print out the complete denture, to lay the basis for further clinical applications.

[Study on the appropriate parameters of automatic full crown tooth preparation for dental tooth preparation robot]

Objective: To further study the most suitable parameters for automatic full crown preparation using oral clinical micro robot. Its purpose is to improve the quality of automated tooth preparing for the system and to lay the foundation for clinical application. Methods: Twenty selected artificial resin teeth were used as sample teeth. The micro robot automatic tooth preparation system was used in dental clinic to control the picosecond laser beam to complete two dimensional cutting on the resin tooth sample according to the motion planning path. Using the laser scanning measuring microscope, each layer of cutting depth values was obtained and the average value was calculated. The monolayer cutting depth was determined. The three-dimensional (3D) data of the target resin teeth was obtained using internal scanner, and the CAD data of full-crown tooth preparation was designed by CAD self-develged software. According to the depth of the single layer, 11 complete resin teeth in phantom head were automatically prepared by the robot controlling the laser focused spot in accordance with the layer-cutting way. And the accuracy of resin tooth preparation was evaluated with the software. Using the same method, monolayer cutting depth parameter for cutting dental hard tissue was obtained. Then 15 extracted mandibular and maxillary first molars went through automatic full crown tooth preparation. And the 3D data of tooth preparations were obtained with intra oral scanner. The software was used to evaluate the accuracy of tooth preparation. Results: The results indicated that the single cutting depth of cutting resin teeth and in vitro teeth by picosecond laser were (60.0±2.6) and (45.0±3.6) μm, respectively. Using the tooth preparation robot, 11 artificial resin teeth and 15 complete natural teeth were automatically prepared, and the average time were (13.0±0.7), (17.0±1.8) min respectively. Through software evaluation, the average preparation depth of the occlusal surface of 11 resin teeth was approximately (2.089±0.026) mm, the error was about (0.089±0.026) mm; the average convergence angle was about 6.56°±0.30°, the error was about 0.56°±0.30°. Compared with the target preparation shape, the average shape error of the 11 resin tooth preparations was about 0.02-0.11 mm. And the average preparation depth of the occlusal surface of 15 natural teeth was approximately (2.097±0.022) mm, the error was about (0.097±0.022) mm; the average convergence angle was about 6.98°±0.35°, the error was about 0.98°±0.35°. Compared with the target preparation shape, the average shape error of the 15 natural tooth preparations was about 0.05-0.17 mm. Conclusions: The experimental results indicate that the automatic tooth preparation for resin teeth and the teeth were completed according to the specific parameters of the single cutting depth by the micro robot controlling picosecond laser respectively, its preparation accuracy met the clinical needs. And the suitability of the parameter was confirmed.

[Three-dimensional data fusion method for tooth crown and root based on curvature continuity algorithm]

OBJECTIVE

To explore a three-dimensional (3D) data fusion and integration method of optical scanning tooth crowns and cone beam CT (CBCT) reconstructing tooth roots for their natural transition in the 3D profile.

METHODS

One mild dental crowding case was chosen from orthodontics clinics with full denture. The CBCT data were acquired to reconstruct the dental model with tooth roots by Mimics 17.0 medical imaging software, and the optical impression was taken to obtain the dentition model with high precision physiological contour of crowns by Smart Optics dental scanner. The two models were doing 3D registration based on their common part of the crowns' shape in Geomagic Studio 2012 reverse engineering software. The model coordinate system was established by defining the occlusal plane. crown-gingiva boundary was extracted from optical scanning model manually, then crown-root boundary was generated by offsetting and projecting crown-gingiva boundary to the root model. After trimming the crown and root models, the 3D fusion model with physiological contour crown and nature root was formed by curvature continuity filling algorithm finally. In the study, 10 patients with dentition mild crowded from the oral clinics were followed up with this method to obtain 3D crown and root fusion models, and 10 high qualification doctors were invited to do subjective evaluation of these fusion models.

RESULTS

This study based on commercial software platform, preliminarily realized the 3D data fusion and integration method of optical scanning tooth crowns and CBCT tooth roots with a curvature continuous shape transition. The 10 patients' 3D crown and root fusion models were constructed successfully by the method, and the average score of the doctors' subjective evaluation for these 10 models was 8.6 points (0-10 points). which meant that all the fusion models could basically meet the need of the oral clinics, and also showed the method in our study was feasible and efficient in orthodontics study and clinics.

CONCLUSION

The method of this study for 3D crown and root data fusion could obtain an integrate tooth or dental model more close to the nature shape. CBCT model calibration may probably improve the precision of the fusion model. The adaptation of this method for severe dentition crowding and micromaxillary deformity needs further research.

Vortex-assisted liquid-liquid microextraction of strontium from water samples using 4',4″(5″)-di-(tert-butylcyclohexano)-18-crown-6 and tetraphenylborate

A vortex-assisted liquid-liquid microextraction method was developed for the chromatographic determination of strontium in aqueous samples. In the method, strontium was complexed with 4',4″(5″)-di-(tert-butylcyclohexano)-18-crown-6 in the presence of tetraphenylborate as the counter anion, which increased the hydrophobicity of the ion-association complex, resulting in its improved extraction into 1-octanol. Strontium from the organic phase was stripped with nitric acid back to aqueous solution and determined by ion chromatography. The optimum microextraction conditions were as follows: 2.0 mL aqueous samples with 3 mM tetraphenylborate; 150 μL of 1-octanol as the extractant phase with 10 mM DtBuCH18C6; vortex extraction time for 10 s; centrifugation at 6000 rpm for 4 min; stripping by 0.1 M nitric acid. Under the optimum conditions, the detection limit for strontium was 0.005 mg/L. The calibration curves showed good linearity over the range between 0.01 and 2.5 mg/L. Intra- and interday precisions of the present method were satisfactory with relative standard deviations of 1.7 and 2.1%, respectively.

Albumin-Gold Nanorod Nanoplatform for Cell-Mediated Tumoritropic Delivery with Homogenous ChemoDrug Distribution and Enhanced Retention Ability

Recently, living cells with tumor-homing properties have provided an exciting opportunity to achieve optimal delivery of nanotherapeutic agents. However, premature payload leakage may impair the host cells, often leading to inadequate in vivo investigations or therapeutic efficacy. Therefore, a nanoplatform that provides a high drug-loading capacity and the precise control of drug release is required. In the present study, a robust one-step synthesis of a doxorubicin (DOX)-loaded gold nanorod/albumin core-shell nanoplatform (NR@DOX:SA) was designed for effective macrophage-mediated delivery to demonstrate how nanoparticle-loaded macrophages improve photothermal/chemodrug distribution and retention ability to achieve enhanced antitumor effects. The serum albumin shell of these nanoagents served as a drug reservoir to delay the intracellular DOX release and drug-related toxicity that impairs the host cell carriers. Near-infrared laser irradiation enabled on-demand payload release to destroy neighboring tumor cells. A series of in vivo quantitative analyses demonstrated that the nanoengineered macrophages delivered the nanodrugs through tumor-tropic migration to tumor tissues, resulting in the twice homogenous and efficient photothermal activations of drug release to treat prostate cancer. By contrast, localized pristine NR@DOX:SAs exhibit limited photothermal drug delivery that further reduces their retention ability and therapeutic efficacy after second combinational treatment, leading to a failure of cancer therapy. Moreover, the resultant unhealable wounds impair quality of life. Free DOX has rapid clearance and therefore exhibits limited antitumor effects. Our findings suggest that in comparison with pristine nanoparticles or free DOX, the nanoengineered macrophages effectively demonstrate the importance and effect of homogeneous drug distribution and retention ability in cancer therapy.

In vivo metacarpophalanageal joint collateral ligament length changes during flexion

We investigated the in vivo length changes of the collateral ligaments of metacarpophalangeal joint during flexion. We obtained computed tomography scans of index, middle, ring and little fingers at 0°, 30°, 60° and 90° of joint flexion from six hands of six healthy adult volunteers. Three of them had their dominant right hand studied, and the other three had their non-dominant left hand studied. We measured and analysed the radial and ulnar collateral ligaments of each metacarpophalangeal joint from the reconstructed images. We found that the dorsal and middle portions of the both radial and ulnar collateral ligament lengthened progressively during digital flexion and reached the maximum at 90° flexion. The length of the volar portion increased from 0° to 30° flexion and then decreased from 30° to 60° flexion, reaching the minimum at 90°. In conclusion, three portions of collateral ligaments on both sides of the metacarpophalangeal joint have variable length changes during flexion, which act to stabilize the joint through its flexion arc.

Size reduction-induced chain breaking in Haldane-chain compounds SrNi2-x Mg x V2O8 (x = 0 and 0.1)

We report size reduction-induced chain breaking in the spin-1 Haldane-chain SrNi_2-x Mg _x V₂O₈ (x  =  0 and 0.1) by magnetization and electron spin resonance measurements. For x  =  0.0, the magnetic susceptibility of all samples can be well described by a temperature-independent term, a Curie-Weiss term and a Haldane-gap term. This implies that a reduced sample grain size breaks the long chain and creates a considerable number of S  =  1/2 edge spins, resulting in the enhancement of magnetization and the decrease of Haldane gap in the samples. These edge spins as well as the other paramagnetic ions at grain boundary and surface might be weakly coupled with each other. For the Mg-doped sample with x  =  0.1, there are more S  =  1/2 spins creased in relative to x  =  0.0 because of a combined effect of lattice defects, Mg-doping and reduced size. In addition, the antiferromagnetic resonance of x  =  0.1 is also presented.

[Application and outlook of three-dimensional printing in prosthetic dentistry]

At present, three-dimensional (3D) printing has been applied in many aspects in the field of prosthodontics, such as dental models, wax patterns, guide plates, dental restoration and customized implants. The common forming principles include light curing, sintering and melting-condensation, the materials include pure wax, resin, metal and ceramics. However, the printing precision and the strength of multi-material integrated forming, remains to be improved. In addition, as a technology by which the internal structure of a material can be customized manufacturing, further advantage of 3D printing used in the manufacture of dental restoration lies in the customization functional bionic micro-structures, but the related research is still in its infancy. The review briefly summarizes the commonly used 3D printing crafts in prosthetic dentistry, and details clinical applications and evaluations, provides references for clinical decision and further research.

[Clinical Analysis of Surgery for Recurrent Cervical Cancer: A Review of 45 Cases]

Objective: To study the efficacy of surgery for recurrent cervical cancer and the influencing factors on prognosis. Methods: To retrospectively analyze the clinical data of 45 patients with recurrent cervical cancer undergoing surgical treatment in our hospital from January 1980 to October 2015, and study their clinical features and prognosis. Results: The Recurrence Free Interval (RFI) of these 45 patients was 3~120 months, and their median RFI was 15 months. Of the 45 cases, 21 recurred inside the radiotherapy field, including 18 with central recurrence and 3 with non-central recurrence; and 24 recurred outside the radiotherapy field, including 16 with pelvic recurrence who did not receive radiotherapy and 8 with distant recurrence. The overall survival time after recurrence of these 45 cases was (39.1±1.0) months, and their 2-year and 5-year survival rates were 55.6% and 22.2%, respectively. The univariate analysis showed that clinical stage, RFI, recurrent site, and initial treatment method affected the survival rate of the patients with recurrent cervical cancer (P<0.05), while the multivariate analysis revealed that recurrent site was an independent prognostic factor for recurrent cervical cancer (P=0.047). Conclusions: Appropriate surgery should be chosen for recurrent cervical cancer according to initial treatment and recurrent site. For patients with central recurrence inside their radiotherapy field, surgery is an effective treatment. Surgery is also suitable for patients without previous radiotherapy and with isolated recurrence, and adjuvant radiotherapy and chemotherapy can improve their survival.

Nanocomposite-Coated Microfluidic-Based Photocatalyst-Assisted Reduction Device To Couple High-Performance Liquid Chromatography and Inductively Coupled Plasma-Mass Spectrometry for Online Determination of Inorganic Arsenic Species in Natural Water

To selectively and sensitively determine the trace inorganic As species, As(III) and As(V), we developed a nanocomposite-coated microfluidic-based photocatalyst-assisted reduction device (PCARD) as a vapor generation (VG) device to couple high-performance liquid chromatography (HPLC) separation and inductively coupled plasma-mass spectrometry (ICPMS) detection. Au nanoparticles were deposited on TiO₂ nanoparticles to strengthen the conversion efficiency of the nanocomposite photocatalytic reduction. The sensitivity for As was significantly enhanced by employing the nanocomposite photocatalyst and using prereduction and signal-enhancement reagents. Under the optimal operating conditions, the analytical detection limits (based on 3σ) of the proposed online HPLC/nanocomposite-coated microfluidic-based PCARD/ICPMS system for As(III) and As(V) were 0.23 and 0.34 μg·L^-1, respectively. The results were validated using a certified reference material (NIST SRM 1643e) and groundwater sample analysis, indicating the good reliability and applicability of our proposed system for the determination of inorganic As species in natural fresh water.

[Effect of low-level laser irradiation on proliferation and osteogenic differentiation of human adipose-derived stromal cells]

OBJECTIVE

To examine the in vitro effects of low-level laser irradiation (LLLI) on proliferation and differentiation of human adipose-derived stromal cells (hASCs).

METHODS

Cultured cells were exposed to different doses of LLLI with a semiconductor diode laser (980 nm; 100 mW-12 W power output). The effects of laser on proliferation were assessed daily up to seven days of culture in cells irradiated for four consecutive days with laser doses of 2, 4, 6 or 8 J/cm², the cells without irradiation were used as controls. Half of the cells were changed to osteogenic medium (OM) when they had grown to 70% confluence. The hASCs both with and without osteogenic supplements were divided into three groups, and each group was irradiated at doses of 0, 2 and 4 J/cm². In order to examine the in vitro effects of LLLI on osteogenic differentiation of hASCs, the alkaline phosphatase activity was assessed on day 7, and alizarin red staining (AR-S) and quantitative detection were assessed on days 14 and 21. The expression of osteoblast master genes (ALP and Runx2) were tested on days 7 and 14.

RESULTS

The proliferation medium(PM)+LLLI4 J/cm² group had the highest multiplication rate. In the groups with osteogenic supplements, LLLI increased alkaline phosphatase activity and mineralized nodule formation, and stimulated the expression of ALP and Runx2. Furthermore, the effect became more obvious at high dose.

CONCLUSION

Our data demonstrated that hASCs proliferation and osteogenic differentiation were enhanced by LLLI. With the increase of laser dose, the effect of LLLI would be enhanced at first, and then be decreased after reaching a peak.